#include <stdio.h>
#include <math.h>

int main() 
{
	double a, b, c;
	double S;
	double A;
	
	printf("please input a b c:");
	scanf("%lf%lf%lf", &a, &b, &c);
	printf("a,b,c:%lf,%lf,%lf\n", a, b, c);
	
	S = (a + b + c)/2;
	A = sqrt(S * (S - a) * (S - b) * (S - c));
	
	printf("S:%lf\n", S);
	printf("A:%lf\n", A);
	
	return 0;
}

